橡胶在动态载荷下的能量损耗分析

以交联密度不同的同类轮胎胎面胶A1和A2为研究对象,通过动态拉伸实验得到储能模量及损耗模量随频率变化的曲线.建立了黏弹性广义Maxwell模型来定量分析不同温度的橡胶在不同频率的动态载荷下的能量损耗.采用非线性规划的方法分别在低频(10~25 Hz)及高频(25~60 Hz)下拟合模量-频率曲线,得到黏弹性广义Maxwell模型的参数值.采用有限元软件Abaqus模拟胎面胶动态拉伸过程并计算胎面胶的损耗角正切,得到不同温度下胎面胶的损耗角正切随激振频率的变化规律,通过和实验结果的比较证明文中所述黏弹性广义Maxwell模型及其参数获取方法可准确应用于胎面胶的动态拉伸性能分析.预测了在不同温度及频率下每一循环载荷周期中胎面胶的应力-应变迟滞回线以及单位体积胶料的能量损耗,阐释了不同温度下的胎面胶的能量损耗随频率的变化规律,同时结合2种胎面胶的交联密度测试数据分析了胶料的构效关系.

Analysis on Energy Loss of Rubber under Dynamic Load

For tire tread rubbers A1 and A2 which were the same kind of rubber but with different cross-linking densities,dynamic tensile experiment was conducted to obtain the curves of storage modulus and loss modulus versus loading frequency.In order to quantitatively analyze the energy loss of rubber under dynamic load with different frequencies and temperatures,a viscoelastic constitutive equation based on generalized Maxwell model was developed.An algorithm of non-linear regression was proposed to fit the curves of dynamic modulus versus loading frequency respectively in low frequency phase (10-25 Hz) and high frequency phase (25-60 Hz).And then the parameter values of storage modulus and loss modulus in the form of generalized Maxwell model were obtained.The dynamic tensile process of the tread rubber was simulated by finite element code Abaqus,and the loss tangent was calculated;hence the changing characteristic of loss tangent under different frequencies was revealed.Through the comparison of experimental results and simulated results of the loss tangent,it was proved that the viscoelastic constitutive model and its parameter determination method could be used to accurately analyze the tread rubber's dynamic tensile performance.Quantitative predictions of the tread rubber stress-strain hysteresis loop and the energy dissipation in a full deformation cycle under different temperatures and frequencies were performed,and then the change rule of the energy dissipation under such circumstance was explained.The results reveal that the energy dissipation of tread rubbers is gradually increased as the loading frequency increases,whereas its dependence on frequency is gradually reduced as the temperature increases.Meanwhile,the structure-function relationship of tread rubber was explored through the comparative testing of cross-linking density.Although the cross-linking density of tread rubber A2 was slightly higher than that of tread rubber A1,the energy loss of tread rubber A2 was larger than that of tread rubber A1 under the same conditions due to the higher proportion of the dangling chain end in the molecular chain.